The embossing of paper products to make those products more absorbent, softer and bulkier, over unembossed products, is well known in the art. Embossing technology has included pin-to-pin embossing where protrusions on the respective embossing rolls are matched such that the tops of the protrusion contact each other through the paper product, thereby compressing the fibrous structure of the product. The technology has also included male-female embossing, or nested embossing, where protrusions of one or both rolls are aligned with either a non-protrusion area or a female recession in the other roll. U.S. Pat. No. 4,921,034, issued to Burgess et al. on May 1, 1990 provides additional background on embossing technologies.
Deep-nested embossing of multiply tissue products is taught in U.S. Pat. No. 5,686,168 issued to Laurent et al. on Nov. 11, 1997; U.S. Pat. No. 5,294,475 issued to McNeil on Mar. 15, 1994; U.S. patent application Ser. No. 11/059,986; and U.S. patent application Ser. No. 10/700,131. While these technologies have been useful in improving glue bonding of multiply tissues and in providing new aesthetic images on paper products, manufacturers have observed that when producing certain deep nested embossed patterns the resulting paper loses a significant amount of its strength through the embossing process. As expected, paper products having this lower strength detract from the acceptance of the product despite the improved aesthetic impression of the deep nested embossing.
It has been found that a new embossing apparatus comprising rounded embossing protrusions can provide a deep-nested embossed paper product which maintains more of its initial strength after going through the embossing process.